1. Field of the Invention
This invention relates to methods of controlling parasitic or otherwise undesired vegetative growths from otherwise desirable plants, which undesirable growths are generally known as plant suckers, and particularly, the invention relates to the use of highly selective herbicidal methods for the selective control of plant suckers on desirable vegetation.
2. Description of the Art
A wide variety of ornamental and fruit bearing plants occasionally sprout undesirable and/or parasitic growths in addition to the established growth pattern of the plant. Such growths all known as plant suckers, so-called because they divert a significant portion of the plant's energy, and thus its ability to produce the desired fruit, flowers, or other ornamental growth. Plant suckers are nonbearing shoots, canes, or limbs that generally emanate from the lower portion of established desiduous, perenial fruit-bearing and ornamental trees and vines, and quite often emanate from the roots at some location other than the established main trunk of the tree or vine. However, plant suckers, in the sense that that term relates to the desirability or the undesirability of vegetative growth, are not necessarily limited to nonbearing growth. Quite often, established trees or vines produce additional bearing growth from their roots or lower main stem portions that is undesirable in that it does not contribute to the established growth pattern of the plant. Thus, such growth, even though it may ultimately bear fruit or ornamental vegetation, is often desirably eliminated.
The growth of plant suckers can occur on essentially all forms of vegetation, although it presents a significant problem primarily in commercial desiduous, perenial ornamental and fruit-bearing orchards and vineyards. The growth of plant suckers is a particularly significant and costly problem in orchards and vineyards in which the main vegetative growth is propagated from dissimilar root stock such as is the case with a variety of citrus, avacado, varietal grape, and other commercial crops. For instance, each year, plant suckers are ordinarily removed by hand from the lower stem portions or roots of varietal grapes shortly after vegetative growth recommences in the spring at a cost on the average of $80 per acre. The manual removal of plant suckers from citrus trees is also customarily practiced, although it is usually required less frequently, i.e., on the order of every 3 to 6 years.
The agricultural industry presently prefers to remove plant suckers manually due to the high potential for harm to the established trees or vines resulting from the use of available herbicides. Most fruit-bearing and ornamental groves and vineyards require years to reach a productive level. For instance, varietal grapes, citrus and avacados usually require at least three and sometimes as many as five years growth before they can produce a commercial crop. Accordingly, growers are understandably hesitant to use any method of sucker control other than manual removal that presents any significant risk of damage to the established plants.
Several contact herbicides are approved by the United States Environmental Protection Agency for use in the control of plant suckers and/or have been used for the control of such undesired growth. Maleic hydrazide (1,2-dihydropyridaziene-3,6-dione), a plant growth regulator, is used to retard sucker growth of tobacco plants. A mixture of n-octanol and n-decanol, sold under the tradename "Sucker Plucker", and the plant growth regulator sold under the name "Sucker Stymie" are also employed to inhibit and/or control sucker propagation in tobacco plants. Dinoseb, which contains the active ingredient 2-sec-butyl-4,6-dinitrophenol, is a contact herbicide which is infrequently used for sucker control in situations which present little risk of damage to existing vegetation. However, the potential toxicity of this compound to desired vegetation and the proximity of plant suckers to such desired vegetation make the use of this compound undesirable in most situations. Spray oils are sometimes employed in an attempt to control plant suckers but are generally not completely effective, possibly due to the fact that the plant sucker continues to be supported by the established plants' root system and therefore can receive energy and nutrients produced by photosynthesis in the unaffected portions of the established plant.
Sulfuric acid is approved for some applications by the U.S. Environmental Protection Agency, i.e., for the control of weeds in growing onions and garlic, and is an effective contact herbicide when applied in sufficient dosages. However, sulfuric acid is consumed by chemical reaction with plant foliage by oxidation and possibly by sulfonation reactions. Furthermore, sulfuric acid is very herbicidally active toward essentially all forms of vegetation which are not protected by a significant waxy cuticle coating. Thus, any over-spray onto the desired foliage of an existing plant, in most cases, will result in substantial damage to the foliage contacted.
Accordingly, a need exists for improved methods for controlling plant suckers that minimizes or eliminates these and other deficiencies associated with existing methods.
It is, therefore, a principal object of this invention to provide improved methods of controlling undesired growth from desired plants.
Another object is the provision of improved methods for controlling plant suckers.
Another object of this invention is the provision of methods for controlling plant suckers which are growing from established, desired vegetation, which methods are relatively nontoxic to the desired, established vegetation, to applicators, or to the environment.
Another object is the provision of methods which quickly and selectively eliminate plant suckers from established ornamental and fruit-bearing trees and vines while minimizing the possibility of damage to the established trees and vines.
Yet another object of this invention is the provision of methods for effectively controlling plant suckers and simultaneously adding significant amounts of plant nutrients and beneficial soil adjuvants to the plant environment.
Another object is the provision of methods for controlling plant suckers which methods are more efficient and are therefore less costly than previously available methods.
Other objects, aspects and advantages of this invention will be apparent to one skilled in the art in view of the following disclosure, the drawing, and the appended claims.